Valve for shock absorbers



May'll, l937 -E. F. RossMAN 2,079,771.

VALVE .FOR SHOCK ABSORBERS Filed Jan. 24, 193e INVENTOR l Wwwa sw lATTORN EYS Patented May l1, 1937V PATENT OFFICE 2,079,771 VALVE FOR SHOCK ABSORBERS vEdwin F. Rossman, Dayton,

General Motors Corporation, corporation of Delaware Ohio, assigner toA Detroit, Mich., a

Application January 24, 1936, Serial No. .60,647

Claims.

This invention relates to improvement in hydraulic shock absorbers.

It is among the objects of the present invention to provide a double-acting shock absorber 5 wi-th fluid ow control devices of simple structure and design, certain of which are adapted to replenish the fluid supply in the uid displacement chambers of the shock absorber and .thus compensate for fluid losses caused by leaks past the piston.

A further object of the present invention is to provide a shock absorber with a replenishing valve, constructed as a unit, which may be inserted into the shock absorber as a complete assembly.

These and other objects of the invention are attained by providing a double-acting hydraulic shock absorber, having a fluid reservoir and two liuid displacement chambers, with fluid flow control devices or spring-loaded valves adapted to be actuated by fluid pressure in each of said valve chambers `to permit a controlled ow of fluid from saidchambers, and with another vfluid flow controlling means constructed as a unit, and adapted normally to shut oli the displacement chambers from the reservoir, -said means being adapted also to be `actuated by the fluid pressure in either one of the chambers to open the other displacement chamber to the reservoir and thus permit fluid to flow from said Areservoir into said chamber.

Further objects and advantages of the present invention will be apparent from -the following description, reference being had to the accom- -panying drawing, wherein a preferred embodiment of the present invention is -clearly shown.

In the drawing:

' Fig. 1 is a plan View 4of the shock absorber, partly in section, illustrating the fluid replenishing valve runit in position with-in the shock absorber.

Fig. 2 is a front elevation of the shock-absorber.

3 is a .longitudinal sectional view of the .fluid valve `on an enlarged scale.

`liig.4 is a view, 'illustrating the valve in longitudinal cross section taken .transversely to that of Fig..3.

Referring :to the drawing, `the yhydraulic shock absorber is shown comprising a casing l2li providing la cylinder 2| and `a fluid reservoir `22. Within lthe cylinder 2l ta :piston :23 iis provided, which forms Adisplacement .chambers 24 and A2t at opposite ends of the shock absorber.

A shaft 30 is journalled transversely of the `shock absorber, one yend thereof extending vout- (el. iss-ss) side the shock absorber and having the operating arm 3l secured thereto. Within the casing, shaft 3i] has an operating cam 32 anchored thereto, this cam extending into a recess in the piston whereby oscillations of the cam 32 will reciprocate piston 23 in the cylinder 2|.

Two Valve chambers 35 and 35 are provided in the casing, val-ve chamber 35 being in communication with the displacement chamber 25 through the duct or passage 37. The valve chamber 3B is in communication with the displacement chamber 24 through the duct or passage 38. Both valve chambers 35 and 36 are provided with spring-loaded check valves which are identical, and only one will be described for the sake of brevity.

Referring to Fig. 1, the valve in the chamber `35 `is designa-ted by the numeral 40, This valve is urged upon its seat to shut off chamber 35 from duct or passage .31 by a .Spring 4I, one end of which engages thle v alvcl, the other abutting against the inner end oi the screw plug 42 threadedly received in the outer end of valve chamber 35. For purposes of description the valve in chamber 35 corresponding to valve 4D in chamber M35 is designated by the numeral 46, Valve chamber 35 is in communication with duct 38 through ,la passage 41 while a similar passage 4B provides vcommunicaticnu between valve chamber :36 and the duct or passage 31. Both valves 4 0 and ,46 normally shut oil communication between their respective Valve and displacement chambers .2 5 and 24, but may be actuated by duid pressure to permit duid to ow from their respective displacement chambers to the displacement chamber at the opposite end of the shock absorber.

4A recess 5.0 is provided in the shock absorber .Casing ifor receiving the fluid replenishing valve. This recess -is in communication with the fluid reservoir 22 via the passage 5|, which opens into the bottom end .of the recess. Duct or passage 43 1 also `communi cat es with the reservoir A through .the passage 52 which Opens into the 4annular side wall ,of recess 5,0. A similar duct or passage 53 provides communication between the displacement chamber 24 and the reservoir 5U, this duct .or passage 53 also opening into the cylindrical sidewall of the recess y5l).

The :means normally `chambers `from the reservoir but adapted to be actuated by the pressure in one of the displacement chambers to connect the other with the reservoir, which `means may betermed the "fluid replenishing valve, comprises a block adapted l closing the displacement to dt into the recess 5d, being held therein in any suitable manner for instance, by an expansible .plug or disc 6|, as shown in Fig. 1. This block 6G has a passage 52 transversely thereof, providing communication between the two ducts or passages 52 and 53, Adjacent the outer surface of the block 53, passage 62 is counter-bored as at 63 at one end and 64 at the other. In the bottom of each counter-bore there is provided an annular ridge, one designated by the numeral t5, the other by the numeral 65, these annular ridges forming valve-seats in their respective counter-bored portions of passage 62. A longitudinal passage 57 communicates with the transverse passage E52, this passage 6l aligning with the passage 5| in the casing when the block is placed in position in the shock absorber casing.

A valve stem 'iii is slidably supported within the passage 62, the diameter of this valve stem being considerably less than the diameter of the passage 62 so as to permit duid flow past the stem. In order to support the stem l@ slidably within the passage E2, two spaced danges 'i3 and M are provided on the stem, rectangular in shape, as shown in Fig. 4, the corners of the rectangle being rounded as at 75 in Fig. 4 forming bearings which slidably engage the inner wall of the passage E2. At each end of the stem there is provided a dexible disc, the one being designated by the numeral 39, the other at the opposite end being designated by the numeral Si. On top of the disc the stem carries a saucer-shaped backing plate, the one for disc 5i) being designated by the numeral 82 and for the disc 8| being designated by the numeral 83. These discs and backing plates are securely held upon the stem 'i3 by peening the ends of the stem over the respective backing plates. When properly assembled upon the stem lil, discs 89 and 3| ,normally engage valve seats 5 and 65 respectively, thereby shutting off communication between the counterbored portions 63 and iid and the main or central portion of the passage S2, and consequently when this unit is in position on the shock absorber casing as shown in Fig. l, communication between the respective passages 52 :and 53 and the reservoir passage 5| will likewise be cut off.

It will be seen that as the arm 3| is moved upwardly or clockwise as regards Fig. 2, the piston 23 will be moved toward the left (see also Fig. 1), consequently the duid in chamber 213, having pressure exerted thereupon, will flow through duct or'passage 3S, urge valve it from its seat, which permits the duid to flow into chamber 36, ,from where it will dow through passages S3 and -37 to the chamber 25. In a similar manner as arm 3| is moved downwardly, or counter-clockwise Vas regards Fig. 2, piston 23 will be moved vtoward the right and, due to pressure thereupon, duid in chamber 25 will be urged through passage 3l against valve iii which, when moved from its seat by a predetermined duid pressure, will permit the fluid to dow into chamber 35, from where the duid will flow through passages il and 33 to the chamber 2li. It has been found that a certain amount of fluid will leak past the piston as it exerts pressure upon the fluid in a displacement chamber and consequently a full supply of fluid will not be delivered to the opposite displacement chamber. To compensate for this loss of duid, a replenishing valve is provided which, when the piston moves toward the left, exerting a pressureupon the duid in chamber 24, will cause fluid to dow through passage 53, exerting a pressure upon `the end of the replenishing valve,

causing the disc-valve to be flexed as it is urged more tightly upon its seat 65, thereby causing the entire valve assembly to move bodily toward the right, which will lift disc-valve 8| from its seat 66 to connect the duct 52 with passages 62 and 61 in communication with the reservoir 22 through the passage 5| in the casing. Under these circumstances theright end of the piston moving toward the left and creating a suction in chamber 25 will tend to draw fluid from the reservoir 22 through passages 5|, 8'! and 62, past the discvalve 8| through the counterbore 64, ducts or passages 52 and 3l to replenish any fluid losses caused by leaks past the piston and to add to the duid supply coming from chamber 24 under these circumstances, for the purpose of completely lling chamber 25. Under the same circumstances as the piston moves toward the right to exert a presure upon duid in chamber 25, the replenishing valve will be moved toward the left as regards Figs. 1 and 3, thus flexing disc-valve 8|, moving disc-valve Si? from its seat 65 and thus permitting duid to dow from the reservoir 22 to the chamber 2li.

The replenishing valve is completely assembled in valve block Gil and thus is inserted into the shock absorber as a complete assembly.

This replenishing valve is actuated by the duid pressure in one chamber to bring the opposite chamber into communication with the reservoir for purposes of duid replenishment. It is of simple construction and the nature of the construction renders it substantially noiseless.

Thus applicant has provided an hydraulic shock absorber having a duid reservoir 22 and two fluid displacement chambers 2li and 25, duid dow from said chambers being adapted 'to be established and controlled by the spring-loaded pressure relief valves fifi and d6, the shock absorber having means in the form of a replenishing valve within block 55V which is adapted to act in response to duid pressure in either chamber 25 or 24 to open the opposite chamber, thereby permitting duid to flow from the reservoir 22 into said opposite chamber for purposes of replenishing the fluid supply, compensating for any duid leaks which may have occurred past the shock absorber piston.

While the embodiment of the present invention constitutes a preferred form, it is to be understood that other forms might be adopted, all coming within the scope of the claims which follow.

What is claimed is as follows:

l. In a hydraulic shock absorber having a duid reservoir and two duid displacement chambers, the combination with a spring-loaded valve adapted to control the dow of fluid from each displacement chamber; vof means normally closing each of said chambers from the reservoir but adapted to be actuated by a slight duid pressure in one chamber to open the other chamber only to the reservoir.

2. In a hydraulic shock absorber having two duid displacement chambers, the combination with a reservoir; communicating ducts connecting both displacement chambers with the reservoir; and means normally closing communication between said ducts to shut olf both chambers from the reservoir but adapted to be actuated by a slight duid pressure in one displacement chamber to establish communication between the other displacement chamber only and the reservoir.

3. In a hydraulic shock absorber having two fluid displacement chambers, the combination With a reservoir; of ducts connecting the reservoir and displacement chambers; and a unitary Valve mechanism normally shutting oi the reser- Voir from both said chambers, but adapted to be actuated by a slight fluid pressure in the one chamber to connect only the other chamber with the reservoir.

4. In a hydraulic shock absorber having two fluid displacement chambers, the combination with a reservoir; of ducts connecting the reservoir and displacement chambers; yieldable means normally closing al1 of said ducts from each other and adapted to be flexed by a slight fluid pressure in one duct to open the other ducts to each other and connect the reservoir and a displacement chamber.

5. In a hydraulic shock absorber having two iluid displacement chambers, the combination with a reservoir; of ducts connecting the reservoir and displacement chambers; a llexible means normally closing each duct; means tying both ilexible means together whereby when one flexible means is flexed by lluid pressure in its duct, the other ilexible means is actuated to open its duct.

6. In a hydraulic shock absorber having two fluid displacement chambers, the combination with a reservoir; of ducts connecting the reser Voir and displacement chambers; a flexible disc valve in each duct; a rigid stem supporting said disc valves so that each valve normally closes communication between its duct and the reservoir; said stern moving one disc valve to open communication between the duct of said valve and the reservoir in response to the flexing of the other disc valve by the iluid pressure in its duct.

7. A hydraulic shock absorber comprising, in combination, a casing providing a fluid reservoir and a cylinder in which a piston forms two fluid displacement chambers, said casing having a recess communicating with the reservoir; a duct leading from each displacement chamber into the recess; a block in said recess, having passages connecting the two ducts with the reservoir; and a unitary valve mechanism in a passage of the block, normally shutting off both ducts from the reservoir, but adapted to be actuated by the iluid pressure in one duct to open the other duct to the reservoir.

8. A hydraulic shock absorber comprising, in combination, a casing providing a fluid reservoir and a cylinder in which a piston forms two iluid displacement chambers, said casing having a recess communicating with the reservoir; a duct leading from each displacement chamber into the recess; a block in said recess, having passages connecting the two ducts with the reservoir; and a unitary valve mechanism in a passage of the block, comprising two flexible disc valves secured to the opposite ends of a stem, said disc valves normally closing the ducts from communication with the reservoir, each disc valve being adapted to be ilexed by fluid pressure in its duct to move the other disc valve to open its duct to the reservoir.

9. A hydraulic shock absorber comprising, in combination, a casing providing a lluid reservoir and a cylinder in which a piston forms two lluid displacement chambers, said casing having a recess and a passage connecting said recess with the reservoir; a duct leading from each displacement chamber into the recess; a block in said recess, having a transverse passage communicating with both ducts and a central passage connecting the transverse passage and the passage in the casing leading from the recess to the reservoir; two oppositely disposed annular ridges in the transverse passage, forming valve-seats; a stem slidably carried in said transverse passage and formed to permit fluid flow through said passage; a disc valve at each end of said stem, each valve normally engaging a valve-seat and being adapted to be urged against the valve-seat and be ilexed by fluid pressure in the adjacent duct to actuate the stem and move the opposite disc-valve from its valve-seat.

10. In a hydraulic shock absorber having a fluid reservoir and two fluid displacement chambers, the combination with means adapted to be actuated by fluid pressure to provide for a flow of fluid from a displacement chamber; of means comprising resilient members normally shutting olf the respective chambers from the reservoir, but adapted to be flexed by the fluid pressure in one chamber to open the other chamber to the reservoir.

EDWIN F. ROSSMAN. 

